1. Field of the Invention
Some embodiments relate generally to monitoring optical channel power in optical networks. More particularly, example embodiments relate to an optical channel monitor for monitoring optical channel power.
2. Related Technology
Computing and networking technology have transformed our world. As the amount of information communicated over networks has increased, high speed transmission has become ever more critical. Many high speed data transmission networks rely on optoelectronic devices for facilitating transmission and reception of digital data embodied in the form of optical signals over optical fibers. Optical networks are thus found in a wide variety of high speed applications ranging from modest Local Area Networks (LANs) to backbones that define a large portion of the infrastructure of the Internet.
Some optical networks implement wavelength division multiplexing (“WDM”) to increase network bandwidth. In WDM optical networks, multiple optical channels occupying distinct wavelengths/frequencies are multiplexed into a single optical signal for transmission across a single optical fiber.
Error rates in long-haul WDM optical networks depend on, among other things, per channel optical power and optical signal to noise ratio (“OSNR”). In long haul WDM optical networks, optical amplification is typically used every 80 km and each optical amplifier repeater plus the cable between the amplifiers degrades the OSNR as well as produces power ripple across the optical band for the transmission channels. As such, WDM optical networks often implement systems that perform optical channel power monitoring and/or optical channel power correction to ensure flat channel powers and low error rates.
Optical channels in some WDM optical networks are spaced at 100 gigahertz (“GHz”) intervals, while optical channels in other WDM optical networks are spaced at 50 GHz intervals, 25 GHz intervals, or other intervals. The higher the channel density, e.g., the smaller the channel spacing, the more difficult it is to accurately measure optical power per channel. Accuracy in measuring optical power per channel also decreases as power disparity among adjacent channels increases.
Some conventional systems for measuring optical power per channel implement tunable filters with non-ideal filter shapes such that bleed-through from adjacent channels contributes significantly to the measured optical power and reduces its accuracy. Other conventional systems for measuring optical power per channel implement arrayed waveguide gratings (“AWGs”) that require numerous photodiodes to measure the optical power of all optical channels and are thus cost-prohibitive in many cases.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced.